Extending formatoptions in vim

Question

With my default settings, theformatoptions flag is tcq for text files, and croql for C++. I don't like that it autowraps the text, so I put this into my vimrc:

autocmd FileType text set formatoptions-=t

So far, this works as expected. Now I want to turn on comment joining on C++, so I add the following line to my vimrc just after the above line:

autocmd FileType c,cpp set formatoptions+=j

Now the formatoptions becomes croqlj for every file, not just C/C++, but also for text. Why is this?

Answer 1

'formatoptions' is a buffer-local option; you should use :setlocal instead of :set.

With the latter, you not only change the option for the current buffer, but also modify the global default for any future buffer that gets opened.